What happens when the peridotite in point X is heated to 1750 °C?

Plate Tectonics Lab Assignment

After reading the introduction to the Plate Tectonics exercises in the lab manual,

complete the questions on a hard copy of this Lab Assignment. When finished, transfer

your answers to the lab quiz in GoVIEW. Do not press the “SUBMIT” button until you

have filled all the answers and are ready to get it graded.

You have two attempts to complete this lab assignment. The average score of your two

attempts will be recorded. You should save each question individually and only press

“SUBMIT” when you are ready to be graded.

Part 1- Lab Manual

The exercises that follow are adaptations of the Plate Tectonics exercises contained in the

lab manual. Note that the number that precedes the text of the question corresponds to the

identifying number of that question in the lab manual.

Lab Manual (Busch 9th Edition) Activity 2.8: The Origin of Magma

1. (Question A1, Figure 2.7) According to the continental geothermal gradient, rocks

buried 80 km beneath a continent would normally be heated to what temperature?

At 80 km depth, rocks will be heated to about _______ degrees Celsius

1. 1500 2. 1000 3. 750 4. 200

2. (Question A2, Figure 2.7) According to the oceanic geothermal gradient, rocks buried

80 km beneath an ocean basin would normally be heated to what temperature?

At 80 km depth, rocks will be heated to about _______ degrees Celsius

1. 1500 2. 1000 3. 750 4. 200

3. (Question A3, Figure 2.7) What is the physical state of the peridotite at point X?

1. 100% liquid 2. a mixture of solids and liquid 3. 100% solid

4. (Question A4, Figure 2.7) What happens when the peridotite in point X is heated to

1750 °C?

1. no change 2. partial melting 3. complete melting

5. (Question A5, Figure 2.7) What happens when the peridotite in point X is heated to

2250 °C?

1. no change 2. partial melting 3. complete melting

6. (Question B1, Figure 2.7) At what depth and pressure will peridotite at point X begin

to melt if it is uplifted closer to Earth’s surface and its temperature remains the same?

1. 75 km, 24,000 atm 2. 65 km, 20,000 atm

3. 40 km, 13,000 atm 4. 20 km, 8,000 atm

7. (Question B2 and B3) When mantle peridotite melts as a result of being uplifted in the

way described in the previous question, the process is called__________ and is likely to

happen at ____________.

1. solidus crystallization, divergent boundaries

2. solution, convergent boundaries and hot spots

3. recrystallization melting, hot spots

4. decompression melting, divergent boundaries and hot spots

8. (Question C, Figure 2.7) According to your answers to the previous four questions

related to the peridotite at point X being subjected to changes in pressure and

temperature, which two processes would lead to melting?

1. decrease in pressure and temperature

2. increase in pressure and temperature

3. decrease in pressure and increase in temperature.

4. increase in pressure and decrease in temperature

Lab manual (Busch, 9th Edition) Activity 2.8 part D: A few modifications will allow you

to run the experiment described in this section using materials readily available in your

home. The hot plate can be replaced by a foil lined frying pan on the stove burner.